Embryology and Development Practice Questions

Q: The diagram given below depicts the various parts from which the diaphragm develops. Defect in which part most commonly leads to congenital diaphragmatic hernia? (AIIMS May 2016)

A. ***A*** - A indicates the **pleuroperitoneal membranes**, which are posterior and lateral structures that form a significant portion of the diaphragm. - Failure of these membranes to fuse with other diaphragmatic components, particularly on the left side, leads to a **Bochdalek hernia**, the most common type of congenital diaphragmatic hernia. *B* - B represents the **septum transversum**, which forms the central tendon of the diaphragm and contributes to the anterior portion. - Defects in the septum transversum can lead to **Morgagni hernias**, which are less common than Bochdalek hernias and are typically anterior and retrosternal. *C* - C indicates the **mesentery of the esophagus**, which forms the crura of the diaphragm. - Defects in this region are rare causes of diaphragmatic hernia and usually involve the posterior medial aspect. *D* - D points to the **muscular ingrowth from the body wall**, which forms the peripheral musculature of the diaphragm. - While essential for complete diaphragm formation, isolated defects in this part are less commonly implicated as the primary cause of major congenital diaphragmatic hernias compared to the pleuroperitoneal membranes.

Q: Portal vein develops from which of these structures? (AIIMS May 2016)

C. The correct answer is A (label C). In this anterior-view schematic, label C represents the right vitelline vein. The portal vein develops from the vitelline venous plexus and its anastomoses around the duodenum, with a major contribution from the right vitelline vein. Label A represents a common cardinal vein. The right common cardinal vein contributes to the superior vena cava and does not form the portal vein. Label B represents the left umbilical vein, located on the subject's left in this anterior view. It carries oxygenated blood from the placenta during fetal life and later becomes the ligamentum teres hepatis; it does not form the portal vein. Label D represents the right umbilical vein, located on the subject's right in this anterior view. It normally regresses during development and does not form the portal vein.

Q: Which of the following marked structures would give rise to the heart?

D. ***D*** - Structure **D** indicates the **splanchnic layer of lateral plate mesoderm**, which gives rise to the **cardiogenic mesoderm** and ultimately the heart. - The splanchnic lateral plate mesoderm is the source of the cardiogenic region, where heart development is initiated during early embryogenesis. *A* - Structure **A** points to the **ectoderm**, the outermost germ layer in this transverse embryonic section. - The ectoderm gives rise to the skin, nervous system, and associated surface structures. *B* - Structure **B** indicates the **intermediate mesoderm** in this transverse embryonic section. - The intermediate mesoderm contributes to the urogenital system, not the heart. *C* - Structure **C** points to the **somatic layer of lateral plate mesoderm** in this transverse embryonic section. - The somatic lateral plate mesoderm contributes to the body wall and limb structures, not the heart.

Q: A young patient with absent thymus presents with tetany and hypoparathyroidism. Which of the following is a marked area in the picture defective in this condition?

C. ***C*** - The image shows the **pharyngeal arches and pouches** during embryonic development. **C** points to the **third pharyngeal pouch**, which gives rise to the **thymus** and inferior parathyroid glands. - A defect in the development of the third pharyngeal pouch would lead to an **absent or hypoplastic thymus** and **hypoparathyroidism**, causing symptoms like tetany due to hypocalcemia. This condition is known as **DiGeorge syndrome**, which results from abnormal development of the **third and fourth pharyngeal pouches**. *A* - **A** points to the **first pharyngeal pouch**, which develops into the **auditory tube** and **tympanic cavity**. - Defects in the first pharyngeal pouch would primarily affect structures in the ear, not the thymus or parathyroid glands. *B* - **B** points to the **second pharyngeal pouch**, which gives rise to the **palatine tonsil** and tonsillar fossa. - Defects in the second pharyngeal pouch are not associated with thymic or parathyroid agenesis. *D* - **D** points to the **fourth pharyngeal pouch**, which gives rise to the **superior parathyroid glands** and the **ultimobranchial body** (parafollicular C cells of the thyroid). - The fourth pharyngeal pouch is also involved in DiGeorge syndrome alongside the third pouch, but the primary structures responsible for the absent thymus and inferior parathyroid deficiency arise from the third pouch.

Q: Nucleus pulposus develops from: (AIIMS May 2018)

D. ***Correct Option D*** - Label D points to the **notochord**, which is the embryonic structure that the **nucleus pulposus** of the intervertebral discs develops from. - The notochord provides transient axial support during early embryonic development and induces the formation of the neural tube. - During development, most of the notochord degenerates, but remnants persist as the gelatinous core of intervertebral discs. *Incorrect Option A* - Label A indicates the **neural plate (neuroectoderm)**, which develops into the **brain and spinal cord**. - It arises from the neural plate, which is induced by the underlying notochord. - The neural plate does not contribute to the intervertebral disc structure. *Incorrect Option B* - Label B represents the **large yolk sac**, a structure involved in early nutrient transfer and the formation of primordial germ cells. - It does not directly contribute to the formation of musculoskeletal structures like the nucleus pulposus. *Incorrect Option C* - Label C points to the **amniotic cavity**, which is the fluid-filled space superior to the embryonic disc. - It does not directly form the nucleus pulposus or other mesodermal derivatives.

Q: For the formation of the shown monozygotic twins, division should take place by

<3 days. *<3 days* - The image shows **dichorionic-diamniotic twins**, which results from division of a single zygote within the first three days post-fertilization, before the formation of the chorion. - This early division results in **two separate placentas** and two distinct amniotic sacs, as depicted in the image. *4-8 days* - Division between 4 and 8 days typically leads to **monochorionic-diamniotic twins**, where twins share a placenta but have separate amniotic sacs. - This results in two distinct, fully separated fetuses sharing a single chorion but each within their own amniotic sac. *8-14 days* - Division between 8 and 14 days results in **monochorionic-monoamniotic twins**, where twins share both a placenta and an amniotic sac. - While sharing a sac, this period usually leads to two distinct, non-conjoined fetuses within that single sac. *>14 days* - Division after more than 14 days results in **conjoined twins**, which results from an incomplete separation of a single zygote after the formation of the embryonic disc. - This very late and incomplete division leads to physically joined fetuses sharing body structures.

Q: Which neural tube defect is shown here:

Anencephaly. ***Anencephaly*** - This image depicts a fetus with anencephaly, characterized by the **absence of a major portion of the brain, skull, and scalp**. - The distinctive features are the **exposed brain tissue** (represented by the light blue and white mass on the head) and the **lack of a developed skullcap** above the eyes. - **Neural tube defect** resulting from failure of the **rostral (anterior) neuropore to close** during weeks 3-4 of embryonic development. - Incompatible with life; most infants are stillborn or die shortly after birth. *Schizencephaly* - **NOT a neural tube defect** - this is a rare **neuronal migration disorder** characterized by abnormal clefts in the cerebral hemispheres. - Results from abnormal neuronal migration during brain development, not from neural tube closure failure. - Does not present with external cranial defects or absence of skull and brain tissue as seen in anencephaly. *Lissencephaly* - **NOT a neural tube defect** - this is a **neuronal migration disorder** characterized by absent or decreased gyri and sulci, giving a smooth brain appearance. - Results from defective neuronal migration during cortical development. - This is an internal structural defect without the obvious external cranial and brain tissue absence characteristic of anencephaly. *Cranioschisis* - Cranioschisis refers to a defect where the **cranium fails to close properly**. - While related to neural tube defects, the image specifically shows **complete absence of the forebrain and skull above the orbits** (anencephaly) rather than simply a skull closure defect with intact but exposed brain tissue.

Q: Name the neural tube defect shown here:

Craniorachischisis. ***Craniorachischisis*** - *Craniorachischisis* refers to a **fissure or defect involving both the cranial vault and contiguous spinal neural tube non-closure**. The image shows significant disruption of the cranial vault and exposed tissue extending to the spine, consistent with this condition. - This is a severe form of neural tube defect, typically occurring in the **earlier stages of neural tube development**. *Cranioschisis* - *Cranioschisis* refers to a **fissure or defect in the skull**, often associated with exposure of brain tissue, but without the contiguous spinal involvement seen here. *Anencephaly* - *Anencephaly* specifically involves the **absence of a major portion of the brain, skull, and scalp**, resulting from failed closure of the anterior neural tube. - The characteristic presentation of anencephaly is a **frog-like appearance** due to the exposed brain and absent vault, which is not fully depicted as such here. *Meningocele* - A *meningocele* is a neural tube defect where the **meninges protrude through a defect in the skull or spine**, forming a sac filled only with cerebrospinal fluid. There are no neural elements in the sac. - The image shows exposed neural tissue rather than a fluid-filled sac, making meningocele an unlikely diagnosis. *Iniencephaly* - *Iniencephaly* is a rare and severe neural tube defect characterized by **extreme retroflexion of the head**, a short neck, and often extensive spina bifida. - The image does not clearly demonstrate the characteristic retroflexion of the head or the severe neck anomalies associated with iniencephaly.

Q: The image shows:

Malformation of vitello-intestinal duct. ***Malformation of vitello-intestinal duct*** - The image depicts a **persistent vitelline (omphalomesenteric) duct** remnant, which can present as a patent duct, fistula, cyst, or fibrous band. The appearance here is consistent with a **patent vitellointestinal duct with prolapsed intestinal mucosa.** - This malformation occurs when the **vitello-intestinal duct**, connecting the developing gut to the yolk sac, fails to involute completely. *Omphalocele* - An **omphalocele** involves herniation of abdominal contents (covered by a membrane) through the **umbilical ring**, while this image shows a solid, polyp-like structure. - The umbilical cord is typically attached to the apex of the sac in omphalocele, which is not what is seen here. *Gastroschisis* - **Gastroschisis** is characterized by uncovered abdominal organs protruding through an abdominal wall defect, usually to the **right of the umbilical cord**. - There is no protective membrane in gastroschisis, and the image shows a covered, distinct growth at the umbilicus, not an open abdominal defect with exposed viscera. *Necrotising enterocolitis* - **Necrotizing enterocolitis (NEC)** is an inflammatory condition of the neonatal intestine, leading to **ischemic necrosis**. - This image shows an external umbilical anomaly; internal intestinal pathology like NEC would present with abdominal distension, feeding intolerance, and bloody stools, not this umbilical lesion.

Q: A newborn presents with a mass in the sacrococcygeal region as shown in the image. Identify the condition:

Sacrococcygeal teratoma. ***Sacrococcygeal teratoma*** - The image clearly shows a **large, tumor-like mass** protruding from the sacral region of the newborn, which is characteristic of a sacrococcygeal teratoma. - These tumors arise from **pluripotent stem cells** in Hensen's node and present as external or internal masses at the base of the spine. *Spina bifida aperta* - **Spina bifida aperta** (e.g., myelomeningocele) involves the protrusion of meninges and/or neural tissue through a spinal defect, usually covered by a thin membrane or skin. - While it occurs in the same region, the mass in the image appears to be a **solid or cystic growth, consistent with a tumor**, rather than exposed neural elements or a meningeal sac. *Cranioschisis* - **Cranioschisis** is a severe form of neural tube defect where the skull bones fail to form, leaving the brain exposed. - This condition affects the **cranium and brain**, not the sacral region of the spine, and therefore does not match the image. *Anencephaly* - **Anencephaly** is a fatal neural tube defect characterized by the absence of a major portion of the brain, skull, and scalp. - Like cranioschisis, it is a **cranial defect** and would not present as a mass in the sacral region.

Question 1

The diagram given below depicts the various parts from which the diaphragm develops. Defect in which part most commonly leads to congenital diaphragmatic hernia? (AIIMS May 2016)

Accepted Answer

A

Answer

B

Answer

C

Answer

D

Question 2

Portal vein develops from which of these structures? (AIIMS May 2016)

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 3

Which of the following marked structures would give rise to the heart?

Accepted Answer

D

Answer

A

Answer

B

Answer

C

Question 4

A young patient with absent thymus presents with tetany and hypoparathyroidism. Which of the following is a marked area in the picture defective in this condition?

Accepted Answer

C

Answer

A

Answer

B

Answer

D

Question 5

Nucleus pulposus develops from: (AIIMS May 2018)

Accepted Answer

D

Answer

C

Answer

B

Answer

A

Question 6

For the formation of the shown monozygotic twins, division should take place by

Accepted Answer

<3 days

Answer

4-8 days

Answer

>14 days

Answer

8-14 days

Question 7

Which neural tube defect is shown here:

Accepted Answer

Anencephaly

Answer

Schizencephaly

Answer

Lissencephaly

Answer

Cranioschisis

Question 8

Name the neural tube defect shown here:

Accepted Answer

Craniorachischisis

Answer

Anencephaly

Answer

Cranioschisis

Answer

Iniencephaly

Answer

Meningocele

Question 9

The image shows:

Accepted Answer

Malformation of vitello-intestinal duct

Answer

Omphalocele

Answer

Gastroschisis

Answer

Necrotising enterocolitis

Question 10

A newborn presents with a mass in the sacrococcygeal region as shown in the image. Identify the condition:

Accepted Answer

Sacrococcygeal teratoma

Answer

Spina bifida aperta

Answer

Cranioschisis

Answer

Anencephaly

Embryology and Development — MCQs

Embryology and Development — MCQs

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